DE10214927B4 - Method for dividing an optical data signal into n electrical data signals with a lower bit rate - Google Patents

Abstract

Method for dividing an optical data signal (ODS) into n electrical data signals (EDS1, EDS2, ... EDSn) with a lower bit rate, characterized in that the optical data signal (ODS) into n identical data sub-signals (DTS1, DTS2, ... DTSn ) that each optical data sub-signal (DTS1, DTS2, ... DTSn) has an optical binary auxiliary signal (OHS1, OHS2, ... OHSn) with the same bit rate and phase as the data sub-signal (DTS1, DTS2, ... DTSn) is added, the nth bit of each of which has a higher level, the n optical auxiliary signals (OHS1, OHS2, ... OHSn) each being out of phase by one bit, so that n sum signals (OSUM1, OSUM2, ... OSUMn ) are generated, each of which is supplied to a decision maker (ES1, ES2, ... ESn) whose decision threshold is above the amplitude of the partial data signal (DTS1, DTS2, ... DTSn) and below the amplitude of the sum signal (OSUM1, OSUM2 ,. ..OSUMn), preferably in the middle between the two amplitudes t, so that each decision maker (ES1, ES2, ... ESn) emits an electrical data signal (EDS1, EDS2, ... EDSn) with 1 / n times the bit rate of the data signal (ODS).

Description

The invention relates to a method according to the preamble of claim 1.

Signals with high data rates over 40 Gbit / s can currently not yet be processed electrically. Therefore, demultiplexing circuits are used the signals of this type into several sub-signals of lower bit rates split.

Use known demultiplexing circuits an optical pulse source, such as an optical voltage controlled oscillator, VCO for short, in cooperation with optical Logic circuits, which often have nonlinear effects in optical waveguides use. Every nth bit is selected from the incoming signal.

One of these arrangements is in the published patent application DE 195 11 819 A1 Described here: A device for demultiplexing an optical data signal is specified, which has a pulse generator, a phase control device and, as an optical switching device, a so-called “nonlinear-optical-loopmirror”, or NOLM for short. The phase control device controls the pulse generator, the pulse of which is in the optical switching device triggers nonlinear optical switching processes, depending on an electrical signal derived from the output of the optical switching device. In this case, every nth bit of the optical data signal is emitted by the nonlinear optical switching device. In addition, an interference source is present in the phase control device, which disturbs the pulse in a defined manner.

Another option is a VCO with controlled electro-optical converters, such as Electro absorption modulators, EAM for short, or Mach Zehner modulators, short MZM to use. The incoming signal is also used every nth bit selected.

Both arrangements have the disadvantage that they are relatively complex and expensive. Also are these arrangements are polarization dependent. It is also a stable one Construction necessary, especially in thermal terms, to avoid runtime drifts to avoid causing bit errors.

The basis of the invention The task now is a simple and stable process for demultiplexing an optical signal into an electrical signal show.

This problem is caused by the im Claim 1 listed Process features solved.

The advantages achieved with the invention consist of demultiplexing an optical signal with simple Means to realize. The process is independent of polarization and insensitive to runtime drifts, since the optical data signal and the auxiliary signal for bit selection via a common optical Transfer the waveguide to the decision maker and both demultiplexing and phase detection take place in the decision maker or the same photodiode.

Advantageous embodiments of the Invention are in the subclaims specified.

The use of a photodiode with adjustable or adjustable working point has the advantage that Decision-makers and opto-electrical converters are implemented in one component.

The use of different Wavelengths, preferably in different optical windows, has the advantage that due to the lack of wavelength related overlap no interference noise with the noise background of the data signal, called amplified spontanous emissions, or ASE for short, occurs what to significantly lower requirements for the signal to noise ratio of the Data signal leads.

The use of a phase control has the advantage that the bits of the data signal are always optimally selected become.

Using a receiver with correspondingly small bandwidth is easier to implement and accordingly cheaper.

The invention is particularly for division the optical data signal into two electrical partial signals, since in this case the pulse source by superimposing two monochromatic signals, For example, laser diodes can be realized, which is special simple and inexpensive is. By using these laser diodes, the frequency and phase control of the auxiliary signal is greatly simplified.

An embodiment of the invention is described below with reference to the figure. It shows:

1 a block diagram of an arrangement for performing the method.

1 shows the basic structure of an arrangement for performing the method according to the invention. The optical data signal ODS to be demultiplexed is fed to a signal divider ST, which divides it into n partial data signals DTS1, DTS2,... DTSn.

The individual data sub-signals DTSi are each fed to a coupler KPi. An auxiliary signal source HSQi generates an optical auxiliary signal OHSi of the same bit rate and phase of the data sub-signal DTSi, which is also the coupler KPi supplied becomes. Every nth bit of the auxiliary signal OHSi has a higher level on. The n optical auxiliary signals are each one bit apart phase. The coupler KPi adds the data sub-signal DTSi and the auxiliary signal OHSi to an optical sum signal OSUMi and passes this on to the decision maker ESi.

The decision threshold of the decision maker ESi lies above the amplitude of the data sub-signal DTSi and below the amplitude of the sum signal OSUMi, approximately in the middle between two amplitudes.

Since only every nth bit of the optical Sum signal OSUMi a higher Level, each decision maker ESi gives an electrical data signal EDSi, which has 1 / n the bit rate of the optical data signal ODS. This becomes a recipient Fed RXi, whose bandwidth 1 / n the bandwidth of the optical data signal is. The recipient RXi gives a demultiplexed electrical data component signal EDDSI at its exit.

So that every auxiliary signal OHSi the has the correct phase with respect to the data sub-signal DTSi from the recipient RXi issued a control signal RSi, the auxiliary signal source HSQi is fed.

For example, a Synchronization to the nth bit in the RXi receiver using code words.

To increase noise To avoid ASE, the optical auxiliary signal is in another optical area / window generated as the optical data signal.

A photodiode is used as the decision maker PHDi used, whose operating point is selected so that only an increased optical Level as it is with every nth bit of the optical sum signal OSUMi occurs in the case of a logical 1, causes a photocurrent, of the recipient RXi is fed according to low bandwidth.

A particularly advantageous implementation results when the optical data signal is divided into two electrical signals, such as 2 shows. The optical auxiliary signals OHS1 and OHS2 can each be generated by modulating or superimposing two monochromatic optical signals MOS1 and MOS2 or MOS3 and MOS4. These signals can be generated by laser LS1, ... LS4. The frequency and phase-accurate auxiliary signal OHSi can advantageously be controlled by a laser control LR1 or LR2.

The two monochromatic optical signals MOS1 and MOS2 or MOS3 and MOS4 become a coupler KPH1 or KPH2 supplied which emits the optical auxiliary signal OHS1 or OHS2.

3 basically shows the same arrangement as 2 , with the difference that the monochromatic optical signals MOS1 and MOS2 or MOS3 and MOS4 are fed directly to the coupler KP1 or KP2.

4 basically shows the same arrangement as 2 , with the difference that the second auxiliary signal OHS2 are generated by delaying the first auxiliary signal OHS1 by the duration of one bit. In this case, only two lasers LS1 and LS2 are required, which have a common laser control LRG. The monochromatic optical signals MOS1 and MOS2 emitted by the lasers LS1 and LS2 are fed to a coupler KPH, the output of which is connected to the input of a signal divider STH which emits an optical auxiliary signal OHS1 or OHS2.

For example, an 80 Gbit / s Signal are demultiplexed, becomes both data sub-signals DTS1 and DTS2 each add one of the auxiliary signals OHS1 and OHS2. The auxiliary signals OHS1 and OHS2 each have a frequency of 40 GHz. This will by modulating two lasers that have a frequency difference of 40 GHz. The absolute wavelengths are the Lasers of minor importance. You should be outside the Wavelength range of the optical data signal to between additional interference noise optical auxiliary signal and the noise background of the data signal, called amplified spontanous emissions, ASE for short.

Claims (10)

Method for dividing an optical data signal (ODS) into n electrical data signals (EDS1, EDS2, ... EDSn) with a lower bit rate, characterized in that the optical data signal (ODS) into n identical data sub-signals (DTS1, DTS2, ... DTSn ) that each optical data sub-signal (DTS1, DTS2, ... DTSn) has an optical binary auxiliary signal (OHS1, OHS2, ... OHSn) with the same bit rate and phase as the data sub-signal (DTS1, DTS2, ... DTSn) is added, the nth bit of each of which has a higher level, the n optical auxiliary signals (OHS1, OHS2, ... OHSn) each being out of phase by one bit, so that n sum signals (OSUM1, OSUM2, ... OSUMn ) are generated, each of which is supplied to a decision maker (ES1, ES2, ... ESn) whose decision threshold is above the amplitude of the partial data signal (DTS1, DTS2, ... DTSn) and below the amplitude of the sum signal (OSUM1, OSUM2 ,. .. OSUMn), preferably in the middle between the two amplitudes This is so that each decision maker (ES1, ES2, ... ESn) emits an electrical data signal (EDS1, EDS2, ... EDSn) with 1 / n times the bit rate of the data signal (ODS). A method according to claim 1, characterized in that at least a decision maker (ESl, ES2, ... ESn) as a photodiode with adjustable or regulated working point. A method according to claim 1 or 2, characterized in that the wavelengths of auxiliary signals (OHS1, OHS2, ... OHSn) not equal to the wavelengths of the optical data signal (DTS1, DTS2, ... DTSn) are. Method according to one of the preceding claims, characterized characterized that the wavelengths the auxiliary signals (OHS1, OHS2, ... OHSn) in another optical Window than the wavelength of the partial optical data signals (DTS1, DTS2, ... DTSn). Method according to one of the preceding claims, characterized characterized that in each case the phase difference between partial data signal (DTS1, DTS2, ... DTSn) and associated Auxiliary signal (OHS1, OHS2, ... OHSn) is regulated. Method according to one of the preceding claims, characterized characterized that the electrical data signals (EDS1, EDS2, ... EDSn) one recipient each (RX1, RX2, ... RXn) with 1 / n times the bandwidth. Method according to one of the preceding claims, characterized characterized in that the optical data signal (ODS) into two data sub-signals (DTS1, DTS2) is divided. A method according to claim 7, characterized in that at least an auxiliary signal (OHS1, OHS2) by modulation or superposition generated two monochromatic optical signals (MOS1, MOS2) become. A method according to claim 8, characterized in that a frequency and phase accurate optical auxiliary signal (OHS1, OHS2) is generated by the frequency and / or the phase of the first and / or second monochromatic optical signal (MOS1, MOS2) regulated becomes. A method according to claim 8 or 9, characterized in that the monochromatic optical signals (MOS1, MOS2) by laser be generated.